1. Field of the Invention
This invention generally relates to a device for supporting a user in a seated position, and in one preferred embodiment, to a chair of the reclining back type. In another preferred embodiment, this invention relates to a chair having automatically adjusting armrests. In a further preferred embodiment, this invention relates to a chair having an adjustable headrest. In a still further preferred embodiment, this invention relates to a chair having an automatically adjusting resistance to tilting that increases in proportion to the weight of the user and as the tilt angle is increased. In a yet further preferred embodiment, the chair has a tilting mechanism which changes the angle of the seat and its support and increases the chair's angle of maximum recline, as well as providing a forward tilting position.
2. Description of the Related Art
Reclining type chairs commonly used in offices usually provide for the back to recline alone, for the seat and back to recline as a unit, or the seat back may recline in a coordinated proportion with the seat. If the back alone pivots, it generally creates a problem known as “shirt tail pull.” This problem is particularly acute if the pivot of the chair back is not coordinated with the natural body action. This problem can also be accentuated by the tendency of the hips of the user to slide forward as the back tilts rearwardly.
In chairs where both the seat and back recline as a unit, in the reclined position there is a tendency to lift the legs of the user from the floor creating an undue pressure by the forward edge of the seat against the underside of the legs of the user immediately above the knee. To overcome this problem the pivot point of the reclining action may be moved forward sufficiently to permit the user's feet to stay on the floor. The undesirable effect of this arrangement is that the body angle between the user's torso and legs is unchanged and as a result, the user's eye level drops undesirably when the chair is reclined.
In any reclining chair, it is desirable that the recline pivot point be at the center of the body or where the user's back normally pivots (i.e., an axis through the user's hip joints). The pivot point of a reclining chair is normally displaced from the ideal pivot point. It is also desirable to have a chair wherein the angle between the user's torso and his legs opens up to relieve internal congestive body pressures. It is, of course, also desirable to provide a chair wherein the user's feet remain on the floor and the recline action parallels the natural body action closely enough to avoid the common shirt tail pull problem.
It is also desirable to provide a chair which is of simplified construction and yet of clean, pleasing appearance emphasizing the isolated and separate appearance of the seat and back with respect to the supporting frames.
My earlier U.S. Pat. No. 4,429,917 shows one approach to solving these problems. U.S. Pat. No. 4,943,114 to Piretti allegedly reports a chair with a compact backrest linkage mechanism that enables the chair backrest and seat to recline.
U.S. Pat. No. 5,251,958 to Roericht, et al., allegedly reports a chair with a synchronous adjusting device that uses the weight of the user to provide a restoring force to return the chair back to an upright position after a user has reclined in the chair.
U.S. Pat. No. 5,486,035 to Koepke, et al., asserts, without providing any showing, that “In such constructions, the difficulty of reclining the chair, i.e., generating the reclining force, increases the further the chair is reclined, and it is common to employ adjusting apparatus for increasing or decreasing the reclining tension of a chair, such adjusting apparatus changing the tension of a spring, or otherwise modifying the reclining mechanism.” Col. 1, 1. 29-34.
While chairs with arms are well known in the art, heretofore, the arms have been either fixed, or adjustable. If the arms were adjustable, any adjustments have been less than ideal and/or quite cumbersome.
Additionally, it was known in the art to put a headrest on a chair, including a reclinable chair. However, such headrests typically provided the chair occupant with very little support, i.e., when the chair is reclined, the headrest maintains its position relative to the back of the chair. Alternatively, if the headrest were to provide the chair occupant with substantial support, the headrest required awkward adjustments.
Moreover, while it is believed that some reclining chairs heretofore available have had a means to adjust their resistance to reclining, such adjustments have been less than ideal, and/or very cumbersome and not practicable.
Instead, rather than confront the processes necessary to adjust their chairs to fit the needs of their particular body build, most users of chairs use them without making any adjustments. Consequently, any ergometric advantages that might be delivered by the properly tuned chair are not achieved. Thus, there remains a need for a chair that is adjustable to the needs of the individual chair occupant without requiring any substantial effort on the occupant's part to effect the adjustments. In other words, a substantially self-adjusting ergometric chair.